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Post by Roverman on Jan 15, 2020 12:02:34 GMT 1
Meriva B A14XER engine (none turbo) 61198 mile. vehicle had a bad misfire scanned & readings came back with misfire on No 4 cyl, removed coil pack & plugs, all plugs nice colour, No 4 plug had slight rust on its top & slight rust on No 4 coil sleave spring, cleaned all the rust off, cleaned & set gap on all plugs fitted plug into coil pack turned engine over & a good blue spark on all plugs, checked all compression's all OK, refitted plugs & coil pack, road tested vehicle pulled well no misfire & no fault codes. Failed mot on c o on 2nd fast idle, tester says it wants new pugs & coil pack ? can a weak coil cause this ? still no fault codes & vehicle runs & pulls well
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Post by rhyds on Jan 15, 2020 12:08:39 GMT 1
Might be worth trying an oil change if the missfire happened for a while, its possible the unburned fuel found its way in to the sump and is affecting the emissions reading.
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Post by Roverman on Jan 15, 2020 18:58:57 GMT 1
The Meriva was serviced at the same mot garage a week before the mot (oil changed then) and the owner was told then that it needed plugs & coil pack and was quoted £200 that's why he asked me to have a look at it. (when serviced plugs & air filter not checked)
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Post by Deleted on Jan 15, 2020 19:45:22 GMT 1
This might come across not being correct, but I have a vauxhall and I don't drive it everyday. The last mot emissions test I was kind of thinking it was going to fail on fast idle CO during the full cat procedure. The car having been stood for a while was very cold (this time of year) and the cat really did take some warming up to get it to work correctly. Maybe yours needs a good Italian tune up to ensure it is hot before hand?
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Post by remmington on Jan 15, 2020 20:36:53 GMT 1
This might come across not being correct, but I have a vauxhall and I don't drive it everyday. The last mot emissions test I was kind of thinking it was going to fail on fast idle CO during the full cat procedure. The car having been stood for a while was very cold (this time of year) and the cat really did take some warming up to get it to work correctly. Maybe yours needs a good Italian tune up to ensure it is hot before hand? AKA "fast roadtest"... |
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Post by chippie on Jan 15, 2020 21:41:53 GMT 1
The engine not being hot enough might not help the cause... What were the emissions readings? You got a printout? 0.3 is the limiti I believe...Anyone confirm? If the engine oil and water temp are bypassed on the analyser, coz the tester is lazy.... I know when I've had my Fiesta tested, the oil/engine temp arent measured..( to my advantage if it passes...  ) |
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Post by studabear on Jan 15, 2020 22:15:34 GMT 1
The engine not being hot enough might not help the cause... What were the emissions readings? You got a printout? 0.3 is the limiti I believe...Anyone confirm? If the engine oil and water temp are bypassed on the analyser, coz the tester is lazy.... I know when I've had my Fiesta tested, the oil/engine temp arent measured..( to my advantage if it passes... ) The basic emission rest doesn't require engine temp to be taken. You just select gauge said warm, fan cut in or coolant pipes hot. A Corsa I would expect fast idle co limit to be 0.20 |
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Post by Deleted on Jan 16, 2020 0:11:42 GMT 1
The engine not being hot enough might not help the cause... What were the emissions readings? You got a printout? 0.3 is the limiti I believe...Anyone confirm? If the engine oil and water temp are bypassed on the analyser, coz the tester is lazy.... I know when I've had my Fiesta tested, the oil/engine temp arent measured..( to my advantage if it passes... ) OBD takes care of that now. |
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Post by Noberator on Jan 16, 2020 2:05:34 GMT 1
The engine not being hot enough might not help the cause... What were the emissions readings? You got a printout? If the engine oil and water temp are bypassed on the analyser, coz the tester is lazy.... I know when I've had my Fiesta tested, the oil/engine temp arent measured..( to my advantage if it passes... ) To pass the basic emissions test the readings must be within all the following limits as below. CO up to 0.2% at fast idle (2,500rpm to 3,000rpm) HC up to 200ppm at fast idle (2,500rpm to 3,000rpm) Lambda between 0.97 and 1.03 at fast idle (2,500rpm to 3,000rpm) CO up to 0.3% at idle (450rpm to 1,500rpm) But Rubyman mentioned it failed the CO on the 2nd fast idle So I would expect the vehicle does not pass the basic emissions test a full cat test or a non-catalyst test as appropriate which includes Check the engine oil temperature to be done.. If it’s below the minimum vehicle specific requirement raise the engine speed to between 2,000rpm and 3,000rpm and maintain this speed until the minimum engine oil temperature has been reached. Remove temperature measuring probe and replace dipstick. Engine oil temperature must be measured whenever possible using the approved device. If in exceptional circumstances the engine oil temperature cannot be measured check that the temperature gauge indicated that the engine was at its normal operating temperature and the cooling fan had cut in or the coolant pipes were hot. Oil temp may be the problem so get it hot hot hot for a re-test.  |
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Post by Roverman on Jan 16, 2020 10:24:13 GMT 1
Thanks for all replies, but I think you are missing the question, did the Meriva need a coil pack when there was no fault codes & it was running perfect, could a week coil pack cause the mot fail ?
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Post by Deleted on Jan 16, 2020 14:13:08 GMT 1
I don't think any of us missed the point, but we know what some testers are like at cutting corners. I think it is most difficult to advise you if a new coil pack and plugs are required, because you do say no fault codes are present and it runs OK.
It might be better if you got someone to have a scan over it with a good scanner and see what if anything shows up?
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Post by Roverman on Jan 16, 2020 15:25:45 GMT 1
No point on a re scan as the tester fitted new coil pack & plugs and didn't give the owner the old coil back, seen the mot results and looks like the first test was done on a cold engine (open loop) ie first test ppm max 200 reading 950 fail second test ppm max 200 reading 50  the owner is happy he as his car back although its cost him a packet. Interesting to read in this months (Feb) mag that the number of corrupt mot's in 2019 was up by three times of 2018  |
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Post by trickydicky on Jan 16, 2020 22:28:01 GMT 1
Sorry I missed this thread
If you think about it
What happens in a cylinder when you have an ignition problem?
Incomplete combustion
The fuel/air dont ignite correctly
So you would see high o2 (because it doesn't get used) and high hydrocarbons (unburnt fuel)
Carbon monoxide is produced when combustion is complete
It sounds like the catalyst wasn't up to temp on the first test!!!
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the owner is happy he as his car back although its cost him a packet.
